Research On Dynamic Characteristics Of Broaching Load Based On Microstructure Of Tool Tip Surface

The broaching processing is widely used in the processing of large-volume parts such as aerospace and automotive fields due to its high precision and high efficiency.With the continuous improvement of the processing precision requirements of industrialization,a large number of scholars at home and abroad are committed to the precision and smoothness of the broaching process.However,the broaching process is the process of the complex interaction between the tool,the workpiece and the chip.Therefore,how to accurately describe the broaching load characteristics after the introduction of the 3D surface microstructure is of great significance for optimizing the parameters in the cutting,improving the tool-work-chip contact conditions and improving the processing quality of the workpiece.In this paper,aiming at how the surface microstructure affects the broaching load characteristics,the horizontal flat broaching machine is used as the test platfonn,and the boring load modeling idea based on the tip surface microstructure is proposed.Starting from the traditional cutting modeling theory,the principle of chip cutting,upsetting and bending deformation is proposed.According to the drag reduction effect introduced by the microstructure and the rib effect induced by the chip ridge,a single tooth broaching load model is established.According to the variation law of the tooth and workpiece contact cycle,a multi-tooth broaching load model is established.The main work of the thesis is as follows:(1)The overall design of the broaching test bench.The hardware part and the software part are designed for the horizontal flat key broaching machine.According to the actual broaching process requirements,the mechanical structure of the basic bed and parts of the broaching machine was analyzed.At the same time,the circuit of the broaching electrical system was designed,and finally the sensor selection was carried out.(2)A broaching load model for the microstructure of the tip surface is established.According to the principle of chip shearing,urging,bending deformation,considering the drag reduction effect introduced by surface microstructure and the rib effect induced by chip bulging,a single tooth broaching load model based on blade surface geometry is constructed.According to the change rule of the cutting contact period of the cutter,a multi-tooth broaching load model based on the geometry of the blade surface was established.(3)Experimental study on the influence of the microstructure of the tip surface on the broaching.Set up a broaching test research platforn,test according to the test plan,collect the workpiece pressure on the machine tool at a frequency of 200 Hz,machine vibration,chips remaining on the tool,and the broaching loads machine tool vibration,and the variation law around the broaching load.Chip changes were analyzed.(4)Numerical calculation and error analysis of the broaching load model.The Matlab is used to simulate the established broaching load model.By comparing the actual broaching load,considering the influence of die number of surface microstructures on the broaching load,the error of the load simulation data and the test data is analyzed,and the drag reduction effect introduced by the surface microstructure and the reinforcement caused by the chip bulge and the effect of the rib effect on the broaching load are discussed.